Under thermal compensation of storage cells, up to now only an arrangement was understood which limits an increase of the oil pressure in the total system as a consequence of a temperature increase. A thermally-caused displacement (for example, of a main mirror in a mirror telescope) was accepted and, if necessary, compensated by focusing the secondary mirror or by readjusting the main mirror.
Known lateral supports with support cells, which lie directly in the line of action of the mirror gravitational plane, function without reversals via levers but can mostly be used only at the outer periphery of the mirror.
By using a lever, the effective plane of the lateral force can, however, be shifted to the rear side of the mirror in the event a lever is used having a fixed pivot point for changing the force direction.
All three points of such a reversing lever should be free of friction forces and have angular-dependent return forces as low as possible. Furthermore, the lateral stiffness should be very high especially of the center joint. For this reason, the stated requirements partially contradict and apparently permit only compromise solutions.
Hydraulic compensation cells (support cells) are known, for example, from European patent publication 0,270,967 or from U.S. Pat. Nos. 4,775,230 and 5,151,809. In these known hydraulic support cells, a center membrane is provided above which the work chamber is configured and below which a compensation chamber lies for the hydrostatic pressure component. Each of the two chambers has a smaller central opening with a seal on the side lying opposite the center membrane. The two chambers are symmetrically built on the two mutually opposite sides of the center membrane in order to obtain the same hydraulic surfaces in both chambers.
Even though such a cell has three sealing systems in the form of membranes (planar membranes or roll membranes), its lateral loadability is so low that a lateral guidance system can only rarely be omitted. Furthermore, roll membranes have unwanted large friction values and spring forces and often become too hard at very low temperatures.